Arne Fjeldstad is an engineer working in the Offshore Structures Section at DNV, located just outside Oslo, Norway. With a background in Mechanical Engineering and a Ph.D. in Fracture Mechanics from the Norwegian University of Technology and Science, Arne brings over 20 years of industry experience. Arne specializes in fatigue analysis of steel structures, conducting reliability analysis, inspection planning based on Risk Based Inspection (RBI) methodology, and performing finite element analysis. He has a strong focus on fatigue analysis and has worked extensively with various applications, including structures, pipelines, risers, subsea applications, mechanical equipment, and pressure vessels. Arne has actively participated in the development of industry standards and currently leads the development of DNV-RP-C203 and DNV-RP-C210.
AbstractDue to the nature of the fatigue phenomena it is well known that small changes in basic assumptions for fatigue analysis can have significant influence on the predicted fatigue lives. Calculated fatigue lives based on the S-N approach are sensitive to input parameters. Fracture mechanics analysis is required for prediction of crack sizes during service life in order to account for probability of detection after an inspection event. Analysis based on fracture mechanics needs to be calibrated to that of fatigue test data or S-N data. Calculated probabilities of fatigue failure using probabilistic methods are even more sensitive to the analysis methodology and to input parameters used in the analyses. Thus, use of these methods for planning inspection requires considerable knowledge and engineering skill. Therefore, the industry requested guidelines that could be used to establish reliable inspection results using these methods. Consequently, DNV performed a joint industry project on establishing probabilistic methods for planning in-service inspection for fatigue cracks in offshore structures. The recommendations from this project were later included in a Recommended Practice (DNV-RP-C210). The essential features of the probabilistic methods developed for this kind of inspection planning and experiences with the use towards floating production, storage and offloading units (FPSO’s) are described in this paper.
|Room 10||Thursday 30th November||13:30-14:00||Arne Fjeldstad|
S12-1 Reliability–based approaches and probabilistic methods
43 - Probabilistic inspection planning for fatigue cracks in floating production, storage, and offloading units